1. Field of the Invention
This invention relates in general to lawn mowers and, in particular, to riding lawn mowers. More specifically, but without restriction to the particular embodiment hereinafter described in accordance with the best mode of practice, this invention relates to an asynchronous steering mechanism for a riding lawn mower that allows the mower to be driven along an arc path having a radius approximately half the length of the mower frame.
2. Discussion of the Related Art
Riding lawn mowers typically include a frame or chassis, front and rear wheel assemblies, a drive motor commonly engaged with the rear wheel assembly to provide drive power thereto, a steering mechanism linked to the front wheel assembly, an operator's seat to place an operator of the mower within easy reach of the mower's controls, and lastly, a cutter assembly located either between the front and rear wheel assemblies or aft of the rear wheel assembly.
One of several important design considerations in such riding lawn mowers includes the turning radius of the vehicle. It is well understood that the turning radius of a riding lawn mower is a function of the combined capabilities of the mower's steering mechanism and front wheel assembly. Prior riding lawn mowers have typically included a rack and pinion steering mechanism such as that shown in U.S. Pat. No. 5,042,238 issued Aug. 27, 1991 to D. M. White, III, et al. This type of prior art rack and pinion steering mechanism includes a steering wheel connected to the upper end of a steering shaft which is downwardly directed through a tower to terminate with a toothed pinion at its lower end. The pinion is engaged with a toothed rack rotatably secured to the mower frame by a pivot rod. A tie rod is linked between the rear of the rack and each front wheel of the mower. This rack and pinion steering mechanism may be designed to provide asynchronous or "Ackerman" type steering in which the front wheel on the inside of the turn is rotated further than the front wheel on the outside of the turn. This allows the mower to be turned through tighter turns.
This type of rack and pinion steering system, however, is situated relatively low to ground level and is susceptible to becoming clogged with grass clippings and mud. In addition, the prior art rack and pinion steering system of the type described and discussed above, is subject to an increased risk of damage when employed in riding lawn mowers with a desired lower profile for vehicle stability.